Vpdsc manual

MicroCal, LLC
22 Industrial Drive East
Northampton, MA 01060 USA
Phone: +413 586 7720
Fax: +413 586 0149

Binding Stability Kinetics support@microcalorimetry.com

VP-DSC MicroCalorimeter
User’s Manual

MAU120030 Rev B

Introduction

Key to Symbols ....................................................................................................................................................iv
Safety.....................................................................................................................................................................v
Instrument Specifications .................................................................................................................................. viii
Safety Specifications ............................................................................................................................................ix
How to Get Help From MicroCal..........................................................................................................................x

Section 1: VP-DSC System Introduction .................................................................1
1.1 VP-DSC Description.......................................................................................................................... 2
1.2 Data Acquisition/Control Description ............................................................................................. 3
1.3 Suitable Laboratory Environment.................................................................................................. 4
1.4 Hardware Connections .................................................................................................................... 5
1.5 ThermoVac ........................................................................................................................................ 7
ThermoVac Accessories ....................................................................................................................................7
Front Panel Controls..........................................................................................................................................8
Degassing Samples ............................................................................................................................................8
Using the ThermoVac for Cleaning.................................................................................................................10

Section 2: Running VPViewer with Origin............................................................13
2.1 VPViewer and Origin Overview .................................................................................................... 14
General Description.........................................................................................................................................14
Operation within a Windows Environment .....................................................................................................14
2.2 Starting VPViewer and the VP DSC ............................................................................................. 15
Opening and Closing VPViewer .....................................................................................................................15
VPViewer and DSC Power Control ................................................................................................................15
2.3 VPViewer and Origin Basics .......................................................................................................... 16
Main Window Display and Description ..........................................................................................................16
Compact Mode ................................................................................................................................................17
Menus and Buttons ..........................................................................................................................................18
Origin For Data Display ..................................................................................................................................19
2.4 VPViewer Cell Status Description ................................................................................................. 20
States of Operation ..........................................................................................................................................20

Section 3: VPViewer and Origin: The Details......................................................23
3.1 The Main Drop Down Menus......................................................................................................... 24
3.2 Main Window Buttons .................................................................................................................... 26
3.3 DSC Control Window ..................................................................................................................... 27
3.4 Thermostat/Calibration Window................................................................................................... 31
3.5 Setup/Maintenance Window .......................................................................................................... 32
3.6 Constants Window .......................................................................................................................... 34
3.7 Origin for Real Time Data Display................................................................................................ 35
Main Window Overview .................................................................................................................................35
VP DSC Customized Buttons..........................................................................................................................36

Section 4: Running The VP-DSC...........................................................................39
4.1: System and Sample Preparation................................................................................................... 40
4.2 Filling/Pressurizing The Cells ........................................................................................................ 41
4.3 Run Parameter Considerations...................................................................................................... 43
i MAU120030 Rev B

Introduction
4.4 Carrying Out Scans......................................................................................................................... 44
Starting the Run ...............................................................................................................................................44
Changing Run Parameters While Running......................................................................................................44
Completion of the Run ....................................................................................................................................44
4.5 Cleaning The Cells .......................................................................................................................... 45
Cleaning Overview ..........................................................................................................................................45
Specific Recommendations .............................................................................................................................45
Cleaning Agents ..............................................................................................................................................46
A Word of Caution ..........................................................................................................................................47
4.6 Maximizing Performance of The VP-DSC.................................................................................... 48
4.7 Isothermal Operation...................................................................................................................... 51
Section 5: Experimental Tutorials .........................................................................54
5.1 Scanning Water/Water ................................................................................................................... 55
Introduction .....................................................................................................................................................55
The Tutorial .....................................................................................................................................................55
5.2 Refilling Tutorial ............................................................................................................................. 65
Introduction .....................................................................................................................................................65
The Tutorial .....................................................................................................................................................65
5.3 Running Lysozyme .......................................................................................................................... 66
Introduction .....................................................................................................................................................66
The Tutorial .....................................................................................................................................................66

Section 6: VP DSC Calibration ..............................................................................68
6.1 Y Axis Calibration Check............................................................................................................... 69
Description of Operation .................................................................................................................................69
The Calibration Procedure...............................................................................................................................69
6.2 Temperature Calibration................................................................................................................ 73
Description Of Operation ................................................................................................................................73
The Tutorial .....................................................................................................................................................73

Section 7: Troubleshooting Guide..........................................................................76
7.1 Site Dependent problems and Considerations .............................................................................. 77
Electrical Interference Through Space ............................................................................................................77
Electrical interference Through Power Source................................................................................................77
Ambient Temperature Fluctuations .................................................................................................................78
7.2 Cell Filling Problems and Considerations..................................................................................... 81
Poor Filling Due to Inferior Technique ...........................................................................................................81
Basic Steps and Considerations During Cell Filling .......................................................................................81
Common Causes of Poor Cell Filling and How to Remedy ............................................................................82
Poor Filling Due to Dirty Cells........................................................................................................................82
Partial Filling Technique .................................................................................................................................82
Heat Capacity Dependencies ...........................................................................................................................83
Refilling in Cycle.............................................................................................................................................84
7.3 Controller Settings and Considerations ........................................................................................ 85
Power Management .........................................................................................................................................85
Task Scheduling and Other Real-Time Conflicts ............................................................................................85
Adding PC Peripherals and Hardware Conflicts .............................................................................................85
7.4 Thermal History and Repeatability ............................................................................................... 87
The First Scan of a Series ................................................................................................................................87
The Run Parameters.........................................................................................................................................87

MAU120030 Rev B -ii-

Introduction
7.5 Known Application Issues .............................................................................................................. 88
The Use of Reducing Agents...........................................................................................................................88
Fluorides ..........................................................................................................................................................90
Precipitation and Aggregation .........................................................................................................................90

Section 8: Operation Below Freezing ....................................................................92
Section 8.1: Operation Below Freezing ............................................................................................... 93
Warning ...........................................................................................................................................................93
Software and Constants ...................................................................................................................................93
Filling ..............................................................................................................................................................93

Section 9: Extended Temperature Range (ETR) ...................................................94
9.1 General Description ........................................................................................................................ 95
Setting Up Your VP-DSCETR Instrument........................................................................................................95
Locating The External Water Bath ..................................................................................................................95
Connecting The External Water Bath To The DSC Cell Unit.........................................................................95
The Bath Plumbing & Condensation...............................................................................................................95
Connecting The External Water Bath To The PC/ Controller.........................................................................96
9.2 External Water Bath ....................................................................................................................... 97
General Description.........................................................................................................................................97
DSC Range of Operation.................................................................................................................................97
Utilizing The Predefined ‘Modes’ of Operation..............................................................................................98
Changing Between The ‘Modes’ of Operation................................................................................................99
9.3 Pressurizing the DSC Cells ........................................................................................................... 100
9.4 Filling the Calorimetric Cells ....................................................................................................... 101
Total Filling –Non Freezing Applications .....................................................................................................101
Partial Filling—Sub Freezing Applications...................................................................................................101
Using The ‘Trigger’ Syringe For Partial Cell Filling ....................................................................................101

Section 10: Compressibility Studies .................................................................... 104
10.1 Introduction to the PPC.............................................................................................................. 105
Unpacking and PPC Inventory ......................................................................................................................105
Setting Up Your VP-DSC and PPC Accessory .............................................................................................106
PPC Accessory Box – Electrical Connections...............................................................................................106
PPC Accessory Box – Plumbing Connections ..............................................................................................106
Final PPC Accessory Configuration..............................................................................................................107
10.2 Introduction to the PPC Application......................................................................................... 108
The PPC Accessory Box................................................................................................................................108
Activating The PPC Mode.............................................................................................................................110
10.3 Setting the PPC Run Parameters............................................................................................... 112
Experimental Parameters ...............................................................................................................................112
Setting The Scan Parameters & Options........................................................................................................113
Scan Edit Mode .............................................................................................................................................113
PPC Scan Parameters.....................................................................................................................................114
Options ..........................................................................................................................................................115
Isoscan Mode.................................................................................................................................................115
10.4 Loading Run Parameters From File.......................................................................................... 117
10.5 Changing the Auto Equilibration Slope Criterion ................................................................... 119
10.6 Technical Information and Tips ................................................................................................ 120
Different Solvents in the Sample and Reference Cell ...................................................................................120
Changes in Atmospheric Pressure .................................................................................................................120
Combining Data Sets Having Different ∆P ...................................................................................................120

iii MAU120030 Rev B

Introduction

Key to Symbols

Symbols used in this manual:

! Warns the user of possible damage to the unit, draws attention to the risk of
injury or contains safety notes and warnings.

Symbols used on the VP-DSC instrument:

Caution: Read the instruction manual before operating

Instrument (supply) ON

Instrument (supply) OFF

Protective Earth (Ground) Terminal

Origin® is a registered trademark of Origin Lab, Northampton, MA

VP is a registered trademark of MicroCal, LLC, Northampton, MA

MicroCal is a registered trademark of MicroCal, LLC, Northampton, MA

Windows™ is a registered trademark of Microsoft Corporation

MAU120030 Rev B -iv-

Introduction

Safety

Operator’s Safety
The points below are intended to enhance your safety awareness and to draw your attention to risks which
only you, the operator, can prevent. MicroCal has set high standards for ourselves in developing and
constructing the VP-DSC. Each unit constructed is fully tested to operational and safety standards. It
should be noted that no amount of design or constructed safeguards can anticipate or prevent improper
handling. It is intended that this instrument be operated only by responsible people trained in basic
laboratory protocol in procedures and safety techniques.

! This product is intended to operate from a power source that does not apply more than 260
VAC rms between the supply conductors or between either supply conductor and ground. A
protective ground connection, by way of the grounding conductor in the power cord, is essential
for safe operation
! To avoid hazard, use only a fuse of the correct type, voltage rating and current rating as
specified on the back of the VP-DSC. This is a 1 Amp 250 Volt Time-lag (Time Delay) fuse.
! Repairs, alterations or modifications must only be carried out by specialist personnel. The
MicroCal Service Department will be happy to serve you for any repair work or operational
questions.
! To enhance safety always plug the instrument into a Ground Fault Circuit Interrupter (GFCI)
device.
! A solution can become an electrical conductor when in contact with electricity and can create a
hazard with the potential of burns or death. Use caution when using solutions near the
instrument and adhere to the following items:
! If any liquid is spilled on or around the instrument unplug the instrument immediately
and wipe it up, if there is any possibility that some of the liquid may have leaked into
the instrument case contact MicroCal immediately. DO NOT PLUG THE
INSTRUMENT INTO ANY POWER MAINS, until the problem is resolved.
! Do not over fill the cell and reservoir. There is a small reservoir located at the top of
the access tubes to catch a minimum amount of overflow, do not exceed the capacity of
the reservoir and allow any fluid to leak into the instrument cabinet.
! This device is not designed to the Medical Devices Directive 93/42/EEC and should not be used
for medical purposes and/or in the diagnosis of patients.
! When using volatile or hazardous solutions in the cells, the operator should always follow
proper laboratory procedures in handling and disposing of such materials (e.g. wear safety
glasses and protective clothing) and always allow the internal cells to cool down to room
temperature before opening the cell port and removing any solutions from the cells.
! All solutions in the cells should be cooled down below 50 ºC before removing from the cells to
prevent the glass syringes from breaking due to the hot liquids.

v MAU120030 Rev B

Introduction

Product Safety
We have used all means to design and produce the VP-DSC to prevent any damage to the instrument
during normal usage. The instrument is solidly built using the latest in micro-technology in its
components and design, but of course, this cannot prevent damage due to physical mistreatment. The
attentiveness of the operator to the identification of materials which could corrode the Tantalum cells, the
prevention of freezing solutions in the cells and the responsible handling and usage of the instrument
should insure a long service life for the VP-DSC.

! The VP-DSC cells are constructed out of a tantalum alloy. Tantalum is extremely resistant to
corrosion by most acids, but like glass, hydrofluoric acid will readily attack tantalum. Any
solution containing the fluoride ion, fuming sulfuric acid or strong bases should be avoided to
prevent corrosion of the cells. Please refer to the accompanying booklet “Corrosion Resistance
of Tantalum and Niobium Metals” for further information.
! The freezing of solutions in filled cells will cause irreparable damage to the cells due to the
expansion of the solution in the cells. If operations below 0 °C are required, the cells should
contain a non-freezing solution or at most 230 µl (half filled) of a solution that could freeze.
! When moving the VP-DSC the instrument should always be in its normal operating or its
vertical position. The instrument should never be moved in a sideways position, due to the
nature of the crystal detectors used for the instruments thermal sensing, which are relatively
strong in a compression mode but weak when subjected to shear stresses. The VP-DSC should
never be dropped or subject to abrupt acceleration or deceleration forces as these forces could
damage the instrument even in its vertical position.

MAU120030 Rev B -vi-

Introduction

European Users: CE Mark
MicroCal VP-DSC calorimeters carry the CE marking which confirms that they meet the applicable
European Community Technical Directives.

Following the provisions of the applicable European council directives:

89/336/EEC, 93/68/EEC Electromagnetic Compatibility

73/23/EEC, 93/68/EEC Low Voltage

Is in conformity with the following harmonized standards:

EN 61326-1:1997, A1:1998, A2:2001 Electrical equipment for measurement, control and laboratory use –
EMC requirements
EN 61000-3-2:2000, A1:2001 Limits for harmonic currents emissions
EN 61000-3-3:1995 Limitation of voltage changes, fluctuations and flicker in low-
voltage systems
EN 61010-1:2001, IEC 61010-1:2001 Safety requirements for electrical equipment for measurement,
control and laboratory use
EN 61010-2-010:2003, Particular requirements for laboratory equipment for the heating of
IEC 61010-2-010:2003 materials

Please refer to the manuals that came with the computer controller for information relating to the CE mark
for this unit.

Instrument Safety Compliance

MicroCal VP-DSC calorimeters carry the CUE Safety Certification
Mark, authorized by TÜV America, a division of TÜV Süddeutschland,
to signify that:

1) the instrument has been tested by an accredited Certification Body
and meets applicable Canadian electrical safety
standards/requirements (CSA/SCC).

2) the instrument has been tested by an NRTL (Nationally Recognized Testing Laboratory) and
meets applicable United States electrical safety standards/requirements (ANSI/UL).

3) the instrument has been tested by a Competent and Notified Body for applicable EU
Directives and meets applicable safety standards/requirements (EN/IEC).

vii MAU120030 Rev B

Introduction

Instrument Specifications
Model or Type : VP-DSC

Performance Specifications
Short Term Noise (RMS average) : 0.5 µcal/°CA
Baseline Repeatability : 1.25 µcal/°CB
Minimum Response Time (high gain) : 7 seconds
Operating Temperature Range : -10° to 130°C

Physical Specifications
Cell Design : Tantalum, 0.5 ml non-capillary
type Fixed in place, non-removable
Dimensions (L x W x H in inches)
Cell : 17 x 8 x 15
Controller : 15½ x 16½ x 7½
Monitor : 9 x 15 x 15½
Weight (lbs.)
Cell : 18
Controller : 25
Monitor : 12
A
Using upscan mode at 90oC per hour with 30 second filter and over a temperature range of 5o to 110oC.
B
Average standard deviation between successive upscans at 90oC per hour with 30 second data point filter over the temperature range 5o to 110o
C. This specification depends on changes in room temperature and was obtained from multiple overnight scans where room temperature at
midnight was lower by ~2.5 oC than the average temperature during daytime. The primary effect of changes in room temperature is to displace
baselines by approximately the same amount at all temperatures, thereby maintaining their parallel nature.

MAU120030 Rev B -viii-

Introduction

Safety Specifications

Instrument Specifications (excluding Controller)
Electrical Specifications
Electrical Ratings:
Voltage : 110 - 240 VAC
Frequency : 50 / 60 Hz
Power : 70 watts

Fuses (2) : Primary=1.0 A, 250 V, Time Delay

Output : Secondary/Data Connection only

Protective Earth Terminals : Internal/external marked

Mode of Operation : Continuous

Classification : Class I
Installation Category : 2
Atmospheric Specifications
Operating:
Temperature : 10° to 40° C
Humidity : L.T. 30% to 75%
Atmospheric Pressure : 700 HPa to 1060 HPa
Pollution Degree : Degree 1
Storage (in original shipping containers with no liquid in cells):
Temperature : -40° to +70° C (no liquid in cells)
Humidity : 10% to 90%
Atmospheric Pressure : 500 HPa to 1060 HPa

ix MAU120030 Rev B

Introduction

How to Get Help From MicroCal
The service department at MicroCal, LLC is available to help you during normal business hours, Monday
through Friday from 8:00 AM to 5:00 PM (EST). Service personnel may be contacted by e-mail, phone
or fax, with the preference being by phone or e-mail. When e-mailing MicroCal for technical assistance it
is always best to attach recent data files (*.dsc, raw DSC data files) which exhibit the symptom of
concern, whenever possible. Also, please include with the correspondence, all details that may be
relevant to the problem. In instances where the problem or question relates to post run data analysis, it is
best to attach the raw data file (*.dsc) and the Origin document (*.opj) generated during data analysis.

There are 2 general categories of problems associated with the VP-DSC and its operation. The most
extreme category is when a system is simply not working, at all. Problems that prevent users from
operating the VP-DSC require immediate consultation with a MicroCal technician. Customers
should not attempt to repair the VP-DSC hardware or software unless instructed to do so by a
MicroCal service representative.

The second, and less extreme general category of problems is when a VP-DSC instrument is functioning,
but is not operating within its normal performance specifications. Poor repeatability, a detectable change
in characteristic baseline position/shape, increase in short term noise level are all examples of
performance problems, typically correctable by the operator. For performance issues such as these it is
recommended that customers carry out the following minimum diagnostic steps prior to contacting
MicroCal for service:

1.) Thoroughly clean cells. Do not assume they are clean. As a minimum, use the provided cell
cleaning apparatus to pass 300 ml of a 10-25% ammoniated detergent solution in water,
followed by 300 ml of cold water rinse, through both the sample and reference cell.
Discretion may call for a more rigorous cleaning procedure as described in Section 4.5 of this
manual.
2.) Refill both the reference and sample cells with filtered, degassed water. Cap and pressurize
the cells.
3.) Go to the Setup/Maintenance window within VPViewer 2000 and activate the debug mode.
While in debug mode, DSC data files will contain all available information produced by the
VP-DSC and often times is helpful in diagnosis of problems.
4.) Carry out a minimum of 4 upscans, in debug mode, with freshly degassed water in both cells.
The more scans recorded, the better the chance of understanding the problem from the data
files. Overnights and weekends are often most convenient for such work. Be sure to use
identical run parameters for all scans. Upscans from 10 to 110 degrees, at 90 degrees/hour,
with a 15 minute pre-scan thermostat period, are acceptable run parameters.
5.) Consult Section 7 of this manual.

If, after completion of the 5 steps listed above, the DSC performance is not corrected, contact the
MicroCal service department for help. The water scans, in debug mode, will then be provided to the
MicroCal service technician for evaluation. Customers will then be contacted by the service department
with comments and recommendations.

MicroCal, LLC Contact Information:
Primary Contact Phone 413-586-7720 Technical support and service at extension 5
Toll Free Phone Number 800-633-3115 Technical support and service at extension 5
Facsimile 413-586-0149 Web Site: www.MicroCalorimetry.com
Please forward corrections or suggestions concerning this manual to info@MicroCalorimetry.com

MAU120030 Rev B -x-

Section 1 - VP-DSC System Introduction

VP-DSC System Introduction

-1- MAU120030 Rev B

Section 1.1 - VP DSC Description

Section 1.1

VP-DSC Description
The VP-DSC is a differential scanning microcalorimeter. The reference and sample cells are fixed in
place lollipop shaped vessels with effective volumes of approximately 0.5 ml. The cells are constructed
from a tantalum alloy and protrude out of the adiabatic chamber via their 1.5 mm (inner diameter) access
tubes. The approximate volume of each cell stem is 0.085mL.

The cell material (Tantaloy 61 TM) has chemical properties quite similar to glass. This alloy is immune to
attack by almost all acids, having been tested under widely varying concentrations/temperatures involving
chlorine, bromine, hydrochloric acid, nitric acid and sulfuric acid. Please refer to the dedicated manual
outlining the chemical properties of Tantaloy 61 TM for more detailed information.

The VP-DSC operates in the temperature range of -10° to 130° Celsius. It is capable of both upscanning
and downscanning with no external heating/cooling source. Scanrates are user selectable and fall in the
range of 0°/hr to +90°/hr. in the upscan mode and 0°/hr to -60°/hr in the downscan mode. The VP-DSC
can also be used at constant temperature for long periods of time (Isoscan) for shelf life studies and/or for
evaluating the stability of drug or other chemical formulations. The duration of such a study is limited
only by the available space on the PC hard disk.

For scanning solutions above their boiling point, the VP-DSC has a self-contained pressurizing system
allowing positive pressures from 0 - 30 p.s.i. Applications requiring higher pressures can be conducted
with the addition of an external pressure source and accessory pressure cap, available from MicroCal.
Pressure applied to the VP-DSC cells should never exceed 80 p.s.i. or irreversible damage to the
cells may be incurred!

Temperature differences between the reference cell and the sample cell are measured, calibrated to power
units and displayed to the user as well as saved to disk. This data channel is referred to as the DP signal,
or the differential power between the reference cell and the sample cell. Calibration of this signal is
obtained electrically by administering a known quantity of power through a resistive heater element
located on the sample cell.

In general, an exothermic (heat is released) event in the sample cell will cause the DP signal to deflect in
the negative direction. Likewise, an endothermic (heat is absorbed) event in the sample cell will cause the
DP signal to deflect in the positive direction.

MAU120030 Rev B -2-

Section 1.2 - Data Acquisition/Control Description

Section 1.2

Data Acquisition/Control Description
The VP-DSC is controlled by two interface boards that reside inside the host PC. The boards are
preconfigured and calibrated at MicroCal, and need no adjustments for operating the VP-DSC.

The data acquisition is handled by a 16 bit A/D (analog to digital) converter board. There are five
differential inputs to the A/D. Jacket temperature, the DP or differential power between the reference and
sample cells, the ∆T or the temperature difference between the cells and the adiabatic jacket, the cell
pressure as set by the self contained pressurizing system and the heat sink power constitute the analog
inputs. All analog input channels may range from -5 volts to +5 volts.

Calorimetric control is handled by the second interface board, a 16 bit D/A (digital to analog) converter
board. Together with the VPViewer software, this board will facilitate automatic equilibration and
repetitive cycling of the VP-DSC with no user interaction.

Although other Windows’ programs can be used while the VP-DSC is running without affecting the data
acquisition or calorimetric control, it should be realized that there are real time operations taking place
during a scan. Performing CPU intensive tasks while a scan is in progress can ‘glitch’ the DSC baseline.
DSC users are encouraged to avoid large file copying to disk drives, large print jobs and recursive control
loops while the VP-DSC is in the midst of an upscan or downscan. Routine data analysis within
Origin® may be performed during DSC runs without regard to compromising the real-time
operations. During the system’s idle state (thermostatting) or pre-equilibration state users should feel
free to use the P.C./Controller in any manner they wish.

-3- MAU120030 Rev B

Section 1.4 – Hardware Connections

Section 1.3

Suitable Laboratory Environment
The VP-DSC with Computer Controller requires about 1 meter length of normal bench space
(ca. 70 cm wide). The ThermoVac degassing station will require another 25 cm of bench
space. This location should be away from strong drafts, room temperature fluctuations,
intense sunlight, vibrations and strong electrical or magnetic fields (as may be produced by an
NMR, microwave oven, large motors or refrigeration units). In addition the mains power
source (115 to 240 VAC) should be properly grounded and free from voltage fluctuations,
harmonic distortions, power dips and spikes. The AC power line should be dedicated to the
MicroCal system and should not share that power with additional equipment.
Although, the power filtering in the VP-DSC instrument is adequate for most laboratory
environments, some disturbances may affect the performance of the instrument and it may be
necessary to have the AC Mains power source evaluated (see table below) or install a power
conditioner. Since power source problems can be manifested in many different ways, it is not
possible to recommend a power conditioner for all situations. It is recommended that you test
a power conditioner, at your location, before you purchase it. If you believe you are
experiencing power source related problems, please contact a MicroCal engineer.

VP-DSC AC Mains Electrical Requirements
Specification Requirement
Voltage 115 to 240 VAC, stable to ± 3%
Regulation
Frequency 0.5% Maximum Deviation
Stability
Power Line < 3% Common Mode or Differential Mode at
Noise any Frequency
Harmonic < 5% Total Harmonic Distortion to 1500 Hz
Content < 3% For any Single Frequency
Ground Noise < 1 VAC Peak-To-Peak
< 2 VAC Ground to Neutral Peak-To-Peak at
any Frequency
Ground < 25 Ohm
Quality

It is emphasized that room temperature fluctuations (i.e. maximum 2.5° C) due to the cycling
on/off of heating and cooling systems, strong air currents, sunlight directly on the instrument
and through space electromagnetic waves may cause subtle performance problems.

VP-DSC Environmental (Operating) Requirements
Temperature 10° to 28° C, constant to 2.5° C
Humidity 0 to 75% Relative Humidity,
non-condensing
Atmospheric 70 HPa to 1060 HPa
Pressure

Section 1.4

MAU120030 Rev B -4-

Section 1.4 - Hardware Connections

Hardware Connections
The cabling necessary to operate the VP-DSC is minimal. Essentially, there is one cable that interfaces
the VP-DSC to the host PC. The cable end with just one 37 pin female connector attaches to the rear of
the VP-DSC cell and is labeled ‘Cell’. The opposite end of the cable will have two 37 pin female
connectors, one for the A/D board, labeled ‘J2’, and the other for the D/A board, labeled ‘J1’.

As you look at the rear of the PC (see below) you will notice that there are two connectors visible in the
two rightmost I/O expansion slots, both being 37 pin male connectors. Looking from the rear, the right-
most of these connectors is for the A/D board (also labeled ‘J2’) while the left-most is for the D/A board
(labeled ‘J1’).

Computer Controller Rear View

J1

J2

J1 Digital to Analog (D/A) Board Connector
J2 Analog to Digital (A/D) Board Connector

Now looking at the cable end having two 37 pin male connectors, one of them is labeled J2 (A/D) while
the other one is labeled J1 (D/A). Connect each of these two connectors to their appropriate 37 pin
female connector at the rear of the host PC.

Connect the power cord to the IEC 320 inlet power receptacle (see next page, labeled 3) on the back of
the cell. Connect the power plug only to a main power supply receptacle with a 3 wire protective Earth
ground and a Ground Fault Circuit Interrupter (GFCI).

Once the VP-DSC cell has been cabled to the PC, it is ready to use. At the rear of the cell unit is a power
on/off switch. This switch must be in the ‘on’ position for the cell to work. This switch is the master
power switch. It can be turned to ‘off’ when the cell will not be used for long periods of time: (i.e.
weekends, holidays, etc.) During frequent ‘on’ periods, the master power may be left on, as the power to
the cell is also under software control and will be turned ‘on/off’ along with the user interface program,
VPViewer. Upon closing the VPViewer application there will be approximately a one minute delay
before the VP-DSC power switches off.

-5- MAU120030 Rev B

Section 1.4 – Hardware Connections

In short, the VP-DSC cell power switch can be left on and the VPViewer software left running. The
software will ensure that the system is safe and does not incur any damage. As an extra precaution it
is recommended that the master power be turned off when the system will not be used for extended
periods of time.

VP-DSC Cell Rear View

1
5
--- O
2

3

MicroCal, Inc.
22 Industrial Drive East
4
Northampton, MA01060
Product
Model
Serial No.

1. Power main switch
2. 2 Power fuses
3. IEC 320 inlet power receptacle
4. Cell Connector
5. Fan

MAU120030 Rev B -6-

Section 1.5-- Thermovac

Section 1.5

ThermoVac
To facilitate degassing samples and cleaning of the cells, you have been provided with the ThermoVac
instrument accessory. The unit is capable of thermostatting a sample at any temperature from 0 to 80 °C,
pulling a vacuum of 28.4 inches of mercury and stirring the sample using small magnetic stir bars.

SAMPLE TEMPERATURE STIRRER
TEMPERATURE
VACUUM SPEED

25.0 250 ON

OFF
TIMER

OFF INCREASE

R
ThermoVac
Sample Degassing and Thermostat
MicroCal TM

Incorporated

ThermoVac Accessories

The ThermoVac and accessories may include, but are not limited to the items listed below. A list of
the actual items shipped with your order will be included in the documentation included with your
shipment.

Quantity Description
1 ThermoVac
3 Stir Bars (Small)
3 Stir Bars (Medium)
2 In-line filters
5 Test Tubes (Small) – for conserving sample volume
5 Test Tubes with Cap (Medium)

-7- MAU120030 Rev B

Section 1.5- ThermoVac

1 Test Tube Holder
1 Flask with Hose & Luer Lock Connector
2 Fuses (1A/250V) 5x20mm Slo-Blo
1 A.C. Mains Power Cord

Front Panel Controls
VACUUM
The ThermoVac is capable of pulling a maximum vacuum of 28.4 VACUUM
inches of mercury. If the VACUUM switch is pushed to the right the
vacuum pump will turn on and remain on for approximately 8 ON TIMER
minutes, then the pump will shut off. If you desire to remove the
OFF
vacuum before the preset time you must push the switch to the OFF
position. When the switch is pushed to the left the vacuum pump
will remain on until it is manually turned off.
TEMPERATURE
Use this dial to set the temperature, in °C, for thermostatting the sample chamber. The
rightmost digit sets the temperature value in tenths of a degree.
SAMPLE TEMPERATURE
Displays the current temperature of the sample chamber.
STIRRER SPEED
This switch will activate a rotating magnetic field that will stir your sample when a small
magnetic stir bar is placed in the tube containing your sample. You may adjust the speed of
the Stirrer motor from 0 RPM (OFF) to the maximum speed of 800 RPM (full turn clockwise).

Rear Panel

1. Power Main Switch
2. Power Fuses
3. IEC Inlet Power Receptacle
4. Vacuum Port
5. Pressure Port

Degassing Samples
Top View of ThermoVac
MAU120030 Rev B -8-


Tube Holder

Vacuum Port

Sealing O-ring Tube Holder
Removal Screw

Vacuum Cap

In-line Filter

To degas the solutions, before placing them into the cells or injection syringe, please do the following.
• Turn on the Power Main Switch.
• Set the desired temperature for the solution.
• Place your solution to be degassed into a test tube, add a small stir bar and place the tube into one of
the open cylinders of the Tube Holder insert.
Please Note: To conserve sample for loading into the injection syringe, use the small test tubes
provided with the ThermoVac.
If you wish to use a tube or beaker larger than will fit into the Tube Holders you may remove the
Tube Holder by simply lifting it up. Due to the tight fit of the Tube Holder, it may be difficult to lift
it out of the sample chamber. In this case you may use a 3/32” hex (Allen Key) wrench to turn the
screw located at the bottom of the center hole of the Tube Holder, to lift the Tube Holder out.
• Turn the stirring on and adjust the speed.
• Turn on the vacuum. Push the switch to the right to activate the vacuum for a preset (ca. 8 minutes)
duration. Push the switch to the left if you wish to manually control the time for the vacuum.
• Place the Vacuum cap on top of the sealing o-ring. The sound of the vacuum pump will change pitch
to indicate the vacuum has sealed the Cap to the o-ring. Once the vacuum has sealed, the Vacuum
Cap will be held firmly in place, till the vacuum pump shuts off.
For the first few minutes after the vacuum pump is turned off, the vacuum in the sample degassing
chamber may remain fairly tight making the removal of the Vacuum Cap difficult. During this
period, the easiest way to release the vacuum is to remove the tubing from the rear Vacuum Port or to
twist off (turn counter-clockwise) the in-line filter.

-9- MAU120030 Rev B


Using the ThermoVac for Cleaning the DSC Cells

The ThermoVac, in conjunction with the cell cleaning device, may be used to circulate cleaning and
rinsing solutions through the calorimetric cells. Follow the proceeding steps to conduct the VP DSC cell
cleaning procedure. Further information is available in Section 4.7 of this manual.

• Insert the long needle into the Sample cell and push down carefully until the o-ring has sealed.
• The end of the upper tubing of the Cell Cleaning Apparatus is immersed into a beaker of 200-400 ml
of detergent cleaning solution.
• The end of the lower tubing is connected to a one liter vacuum flask through the #8 rubber stopper.
• The side arm of the vacuum flask is attached to the Vacuum Port of the ThermoVac. Your Setup
should look like the picture below.

• Turn on the ThermoVac vacuum pump. The vacuum will pull the detergent solution from the beaker,
through the cell and into the waste flask. NOTE: DO NOT ALLOW THE VOLUME OF FLUID
IN THE WASTE FLASK TO ACCUMULATE SUCH THAT IT WOULD RISE UP TO THE
LEVEL OF THE SIDE ARM AND BE SUCKED INTO THE THERMOVAC’S VACUUM
PUMP. THIS MAY CAUSE THE PUMP TO BECOME DAMAGED.

MAU120030 Rev B -10-


• Once sufficient detergent solution has passed through the cell, the hose is removed from the solution,
rinsed free of detergent using a plastic wash bottle, and then placed into another beaker containing ca.
200-400 ml of water for rinsing.

• After rinsing with water, remove the tube from the rinse water and allow time for the vacuum to drain
the fluid out of the hoses, then remove the cleaning apparatus from the cell.

• Remove the remaining water from the cell by using a long needle syringe. If there is any residual soap
in the cell reservoir, be sure to rinse it clean with a long needle syringe and water.

We do not recommend drying the cell before filling with your sample solution, but it should
be rinsed twice with the buffer you are using for the experiment. Finally, it should be
completely drained and filled with your sample solution in the manner described in section
4.2. Because a small amount of the buffer used for final rinsing will adhere to the walls of the
cell and act to dilute your sample solution, you may wish to correct for this by lowering your
sample concentration by 2% if you measured concentration before the sample was introduced
into the cell.

-11- MAU120030 Rev B


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MAU120030 Rev B -12-

Section 2—Getting Started With VPViewer and Origin

Getting Started With VPViewer™ and Origin®

-13- MAU120030 Rev B

Section 2.1 --VPViewer and Origin Overview

Section 2.1

VPViewer and Origin Overview

General Description
All control of the VP-DSC is handled by the front-end software application, VPViewer. It is within
VPViewer that all DSC experimental parameters are defined, DSC scans are started and stopped, real time
hardware operations are performed, and DSC data is saved to the hard disk of the PC/Controller. By
default, all data that is generated in the scanning state of a DSC scan will be saved to disk, with no user
interaction.

Operation Within a Windows™ Environment
Only one copy of VPViewer will be permitted to run at any given time. If a second instance of the
application is detected then VPViewer will immediately terminate itself. Users should feel free, however,
to run Origin for data analysis simultaneously with VPViewer, as well as most other Windows
applications. In general, VPViewer is a multi-tasking application with some subtle limitations. If
VPViewer detects a conflict that may jeopardize its ability to acquire data, it will inform you of this
conflict. In such instances you should contact MicroCal.

Although other Windows’ programs can be used while the VP-DSC is running without affecting the data
acquisition or calorimetric control, it should be realized that there are real time operations taking place
during a scan. Performing CPU intensive tasks while a scan is in progress can ‘glitch’ the DSC baseline.
Users are encouraged to avoid large file copying to disk drives, large print jobs and recursive control
loops while the VP-DSC is in the midst of an upscan or downscan. Routine data analysis within
OriginTM may be performed during DSC runs without regard to compromising the real-time
operations. During the system’s idle state (thermostatting) or pre-equilibration state users should feel
free to use the P.C./Controller in any manner they wish. See the Section 7 of this manual for additional
information.

MAU120030 Rev B -14-

_______ ___ Section 2.2 – Starting VPViewer and the VP-DSC

Section 2.2

Starting VPViewer and the VP-DSC
Opening & Closing VPViewer
The VPViewer application is started via an icon on the Windows desktop or through the start menu in
windows. To start VPViewer from the desk top, double click on the icon for VPViewer 2000. To use the
start menu, select start/programs/MicroCal’s VPDSC/VPViewer VPDSC.

When the VPViewer application is started it will always open a second application, MicroCal’s Origin.
This specific instance of Origin will be dedicated to displaying the real time data generated by the VP-
DSC. Both prescan equilibration data, as well as data obtained from the scan itself will be displayed in
real time in this instance of Origin. Users do not need to concern themselves with ‘saving’ any of the data
they see within the real-time instance of Origin, as VPViewer will always save experimental data to the
hard disk, automatically. VPViewer will also close the real-time instance of Origin when VPViewer itself
is closed. If the real-time instance of Origin is closed by accident, an error message will appear and the
real-time data display will be lost until VPViewer is closed and reopened. Since all data will still be
saved to disk, it is recommended that the user wait for the current series of DSC scans to complete prior
to closing and reopening VPViewer.

VPViewer and DSC Power Control
The main power for the VP-DSC cell unit is controlled by the VPViewer software application. The
presence or absence of power to the cell unit is indicated by the Power LED located on the front panel of
DSC cell. When the power to the cell unit is on, the LED will shine bright orange and when the power to
the cell unit is off, then the LED will also be off. In order for the cell unit power to turn on, the cell must
be plugged in, the power switch at the rear of the cell must be in the on position, and VPViewer must be
opened and running. Upon opening the VPViewer application, it may take several seconds for the DSC
cell power and the Power LED to come on. Likewise, after closing VPViewer it will require a minute or
so for the cell power and Power LED to turn off.

When the instrument is first powered up, VPViewer will momentarily display erroneous data values. The
reason is that upon initial power up, the amplifiers will saturate their outputs for a short period of time
independent of the input signal to the amplifiers. As a rule, the temperature display will initially be about
17 degrees higher than the actual temperature. After a minute of so the reading will settle to the actual
value. If VPViewer detects a temperature value that could be potentially dangerous to the instrument, it
will force the cell into an error state. If this should happen upon the initial power up of the system,
simply wait for the temperature value to settle (about 1 minute) and clear the error state from the main
menu. Normal operation is now possible.

The VP-DSC was designed to be left with its power on for extended periods of time. This will allow for
the DSC electronics to remain at the appropriate operating temperature even when the DSC is not actually
carrying out scans. It is only recommended that the power to the DSC cell unit be turned off during
extended periods of down time, such as holidays and vacations.

-15- MAU120030 Rev B

Section 2.3 --VPViewer and Origin Basics

Section 2.3

VPViewer and Origin Basics
Main Window Display and Description
The main window of VPViewer for the VP-DSC is depicted below.

As can be seen by the above picture, VPViewer displays three data channels by default. The data
channels are defined as follows:

Temp (Celsius): The current temperature, in degrees Celsius, of the calorimetric cells.

DP (mCal/min.): The differential power, in mCal/min., between the reference cell and sample cell.
Positive DP values means that the reference cell is hotter than the sample cell while negative DP
values means that the sample cell is hotter than the reference cell. In terms of reactions (assuming

MAU120030 Rev B -16-

_______ ___ Section 2.3 –VPViewer and Origin Basics

they take place in the sample cell), exothermic reactions will cause the DP to deflect in the
negative direction while endothermic reactions will cause the DP to deflect in the positive
direction. The power units for the DP data channel may be displayed in mCal/min., µCal/sec. or
µWatts, as can be seen later in this section.

Press. (p.s.i.): The current pressure of the cells in pounds per square inch, as set by the VP-DSC self
pressurizing system.

In addition to the three default data channels, VPViewer makes available to the user three additional data
channels. To view the three additional data channels, double click on the Pressure data (the actual
numeric data in the display box) and the three additional data channels will be displayed, as pictured
below:

The additional channels now displayed are the DeltaT, HeatSinkT and the time. These data channels are
defined as follows:

DT or Delta T (degrees C.): The current temperature difference, in degrees Celsius, between the adiabatic
jacket and the calorimetric cells (average of both cells). Negative Delta T values indicate that the
cells are hotter than the jacket, while a positive Delta T indicates that the jacket is hotter than the
cells.

HeatSinkT(no units): A numerical indicator of heat sink function inversely proportional to the actual
temperature. This value is only relative and is used for troubleshooting.

Time (sec.): If the VP-DSC is in a prescan (equilibration) or a scan, then the current time into that prescan
or scan, in seconds, will be displayed.

Once the additional data channels are displayed, double clicking on any of the three additional data
channels will toggle the display back to the default channels only.

Located above the data channel boxes and in the frame which holds all data channel boxes, the current
status of the VP-DSC is displayed (Cell Status Indicator). The VP-DSC works by progressing through a
series of states, each state having a specific objective. Once the objective of the current state is achieved,
the DSC proceeds to the next state. It is a good idea for all users to be generally familiar with the
objective of each state as well as the criterion for exiting each of the states. For a detailed definition of
each state, please refer to Section 2.4 of this manual.

Compact Mode

-17- MAU120030 Rev B

Section 2.3 --VPViewer and Origin Basics

The large buttons at the top of this window provide easy access to commonly used features. The features
are unavailable if they are shaded but will become available to the user when the particular function is
appropriate to use. An exception to this is the Compact Mode button, which will always be available to
the user. This button will shrink VPViewer’s size down and allow it to fit easily with Origin on the
desktop. VPViewer’s size is limited to the compact mode size or the standard mode size and can not be
manually resized by the user. The compact mode is displayed below.

Menus and Buttons
VPViewer provides users with three types of controls for accessing all of the application’s functionality.

The main drop down menu selections generally control global system functions.

The Main Window Buttons allow easy access to features that are frequently used, similar to a toolbar.

The main window tab selections toggles the active display between one of the four main windows.

The details of each of these sections are provided in Section 3 of this manual.

MAU120030 Rev B -18-

_______ ___ Section 2.3 –VPViewer and Origin Basics

Origin For Data Display
All equilibration (prescan) data and actual scan data is automatically plotted in the copy of Origin opened
by VPViewer for users to view. The document name within this instance of Origin will always be
VPDSCPLOT.OPJ, and that name is visible in the Origin window border.

In general, double clicking on any Origin object will give you access to the details of that object. For
instance, double clicking on the X Axis will open up the X Axis dialog box where the range, color and
various other details of the axis may be changed. Similarly, plot details can be accessed by double
clicking on any plotted data set. For more details on changing the characteristics of the plot window and
its contents, please refer to the Origin® User’s manual. Further details are also given in Section 3.7 of this
manual. The default Origin plot window is displayed below:

-19- MAU120030 Rev B

Section 2.4-VPViewer Cell Status Descriptions

Section 2.4

VPViewer Cell Status Descriptions

States Of Operation
The VP-DSC is a state driven instrument, with the functionality of the states being controlled by
VPViewer. The current state of the DSC (cell status) is always displayed both in VPViewer and Origin,
as show in the previous two graphs.

To understand the way in which the VP-DSC will progress through a pre-run equilibration and
subsequent run (or scan), one need only understand the general purpose of each of the cell states as
reported by VPViewer. In general, there are 4 types of states: idle, prerun, run and postrun.

When the VP-DSC is not busy equilibrating or scanning, it sits in its idle state, namely the thermostatting
state. While in the thermostatting state, the only objective for the VP-DSC is to go to, and maintain, the
currently defined thermostat temperature. The VP-DSC will remain in its idle state until the operator
starts a scan or a series of scans. Access to the current thermostat temperature is obtained through the
Thermostat/Calib. Main window tab.

Upon starting a scan or series of scans the VP-DSC will exit the idle state and will proceed to the first
prerun state. The objective of the first prerun state will be in getting the VP-DSC cells and adiabatic
jacket to the desired starting temperature for the first scan. This will be indicated by a cell temperature
that is very close to the requested starting temperature (within 0.5 degrees), and by a DeltaT (temperature
difference between cells and adiabatic jacket) which is very close to 0 degrees (< 0.1 Deg.). To save
equilibration time it is usually best to set the VP-DSC thermostat temperature to be the same as the
starting temperature for scan #1.

Once the cells and jacket have settled very close to the requested starting temperature, the DSC will enter
the 2nd prerun state which is the prescan thermostat state. The behavior in the prescan thermostat state is
the same as in the idle state, in that the VP-DSC will simply maintain the requested starting temperature,
for the requested period of time. The purpose of this state is to allow for thermal gradients within the
DSC cell unit to minimize so that there is very little heat flow within the thermal core of the DSC. The
default prescan thermostat period of 15 minutes is recommended.

After the prescan thermostat period has elapsed, VPViewer and the DSC cell will proceed to the final
prerun state, the final baseline equilibration. Upon entering this state, the heating (upscan) or cooling
(downscan) of the DSC is activated and the equilibration of the DSC is temporarily perturbed. The
purpose of the final baseline equilibration state is to allow for re-equilibration of the DSC. Since the DSC
is already scanning, several degrees of data will be needed to achieve a stabilized baseline as the DSC
heats or cools. In general, it will always require less than 5 degrees of data for re-equilibration. This
should be anticipated by the user in the setting of the run parameters. For instance, if the operator
specifies that an upscan begin at 10 degrees, the data file will contain equilibrated baseline data beginning
at approximately 12-15 degrees (depending on scan rate). There is no avoiding this and users must
request starting temperatures which are slightly lower than the temperature at which they wish to save
useful data.

MAU120030 Rev B -20-

_______ ___ Section 2.4 – VPViewer Cell Status Descriptions

After the final baseline equilibration period has elapsed the DSC enters the scanning state. Although the
DSC cell was scanning in the final baseline equilibration state, now it will be equilibrated and saving
DSC data to disk. The scan will continue until the requested ending temperature of the scan is achieved.
Upon completion of the actual scan, the VP-DSC can make use of one post run state, the post-run
thermostat period. Users may specify time period for post run thermostatting. This state is typically used
only for cleaning purposes, in order to incubate the DSC cells at a high temperature for a specified period
of time. In general, there are no performance gains to be had by specifying a post-run thermostat period
during normal DSC operation.

If the recently completed scan is the last scan of a series, the DSC returns to the idle state and resumes
thermostatting at the ‘Post Cycle Thermostat’ temperature. If it is not the last scan of the series then the
DSC returns to the first prerun state for the next scan and prepares to carry out another equilibration and
scan, as specified in the Experimental Control window.

-21- MAU120030 Rev B

Section 2.4-VPViewer Cell Status Descriptions

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MAU120030 Rev B -22-

_______ ___ Section 3 – VPViewer and Origin: The Details

VPViewer and Origin: The Details

-23- MAU120030 Rev B

Section 3.1—The Main Drop Down Menus

Section 3.1

The Main Drop Down Menus

The main drop down menus at the top of VPViewer will allow for access to some of the less frequently
used functions of the application. You will find that the exact sub menu selections may change (DSC
menu only) and will depend on the current state of the instrument. Each main menu selection is outlined
below with their specific sub menus detailed.

System: Quit Program. Selecting Quit Program prompts the user once to see if they want to terminate
the VPViewer application. Responding with yes will terminate the program and any scans in
progress. All DSC scans, or partial scans that have been completed will already have been
saved to disk. Approximately a minute or so after program termination, the power to the VP-
DSC will also be shut down. Power to the VP-DSC will not be restored until the VPViewer
application is run again.

DSC: DSC Scan Mode. Allows the user to change between the available modes of operation for the
VP-DSC. The DSC Controls window will change according to the mode that is selected. The
default mode of operation is Conventional DSC where the cells and jacket are scanned up or
down at a constant scan rate.
All VP-DSC users also have access to the Isothermal Scan Mode where the DSC is kept at a
constant temperature for a specified period of time. This mode of operation is useful for
monitoring long, slow thermal processes, common in shelf-life studies, cell metabolism and
enzyme kinetics. Please refer to Section 4.7 of this manual for details on the IsoScan Mode of
operation.
The third mode of DSC operation, Compressibility Mode, is only available to those users who
have purchased the PPC (Pressure Perturbation Calorimetry, patent pending) instrument
accessory. By using the VP-DSC together with the PPC accessory, scientists can now study the
volumetric properties of biopolymers in dilute solution. Please refer to Section 10 of this
manual for details on the Compressibility Mode of operation.

Print/Save As Text Run Parameters. This function allows users to print or save to a file the
run parameters that are being used for a series of DSC scans. While run parameters are always
included as part of the DSC data file header, the Print/Save As Text Run Parameters menu
option provides the user with a nicely formatted listing of run parameters, ideal for data
presentation or general record keeping.

MAU120030 Rev B -24-

_______ ___ Section 3.1 – The Main Drop Down Menus

Start Calibration Run. This option is used to check the accuracy of the DSC y-axis
measurements (DP signal). Please refer to Section 6.1 of this manual for details on y-axis
calibration.

Help: Help. Allows access to the help menus. At the time of release of this User’s Manual the on-
line help was still under development.

About. Provides specific details about this version of software and contact information for
Microcal, LLC.

-25- MAU120030 Rev B

Section 3.1—The Main Drop Down Menus

Section 3.2

Main Window Buttons
The main Window buttons allow access to VPViewer’s frequently used functions. These buttons are
displayed below and the details of each button’s function are described in detail. Be aware that this graph
shows all the buttons available for use. Normally some of the buttons would be grayed out and not
available depending on the current state of the instrument. Specifically, the Start button is only available
when the DSC is in its idle state. Similarly, the Stop, Update Run Param. and Display Run Param.
buttons are only available when the VP-DSC is active, in a prescan, scan or postscan state.

Load Run File: Displays the file open dialog box that allows for loading previously saved run
parameters. Run parameters may be loaded from one of two types of files. They may be loaded from a
setup file (*.scn, *.iss, *.pps) which was previously saved from the experimental control window. Run
parameters may also be loaded from a data file (*.dsc, *.iso, *.(scan#)), with the run parameters being
extracted from the data file header.

Save Run File. Displays the file save dialog box which allows saving of the currently displayed run
parameters. By saving the run parameters to a setup file (*.scn, *.iss, *.pps) they may be reloaded and
reused in the future by selecting Load Run File as described above

Display Run Parameters. Displays the current run parameters for the scans that are currently being
executed. Available only when the VP-DSC is in a non-idle state.

Update Run Parameters. Updates the current run parameters for the scans that are currently being
executed. This function allows you to change parameters for the scans while they are in progress.
Available only when the VP-DSC is in a non-idle state. It should be realized that changing of run
parameters while the DSC is in a non-idle state will have no effect on the current series of DSC scans,
unless the Update Run Params. button is clicked.

Start. This button is used to start a series of DSC scans, as currently defined in the DSC Controls
Window. Available only when the VP-DSC is in its idle state.

Stop. This button terminates the current scan and series of scans. Available only when the VP-DSC is in
a non-idle state.

MAU120030 Rev B -26-

_______ ___ Section 3.3 – DSC Controls Windows

Section 3.3

DSC Controls Window

The DSC Controls window is the main access point for operating the VP-DSC instrument. This window
will change its content when you change the DSC Scan Mode. The graphic below shows the DSC
Controls window as it appears in Conventional DSC mode. Details for the other modes of operation can
be found in Section 4.7 (IsoScan mode) and Section 10 (Compressibility mode) of this manual.

Found below is a definition for each of the run parameters displayed in the DSC Controls window, while
in the Conventional DSC Mode.

Number of Scans: Determines the number of scans in the series. There may be between one and two
hundred scans in a series, comprised of upscans and/or downscans. All scans of a series will be
carried out automatically once the first scan is started from the menus, unless the series is
terminated via the menus prior to completion.

Post Cycle Thermostat: The temperature that the VP-DSC will go to after the last scan of the series is
complete. The cell will remain at this temperature until the currently set Thermostat Temperature
is changed, or until another series of scans is started.

-27- MAU120030 Rev B

Section 3.3—DSC Controls Windows

Cell Concentration: This is the concentration (mM) of the solution in the sample cell. The value is stored
in the data file header, read by the data analysis program and used in various analytical
calculations. This value is only used during data analysis and need not be entered if no data
analysis is to be performed (i.e. water/water scans, calibration scans). If the concentration is not
entered or is entered incorrectly, it can be changed within the data analysis program.

Once the Experimental Parameters have been defined, one would next set the Scan Edit Mode. This
determines if all scans of a series are to be identical, or if each scan may potentially have unique scan
parameters. The Scan Edit Mode is set by clicking on the appropriate button, with each setting being
defined below:

Identical Scans: Sets all scan parameters for all scans of the series to be identical to those scan
parameters of the currently selected scan. The currently selected scan is that scan number which
is highlighted in the list box at the bottom of the Experimental Control window. Additionally,
while this button is selected then all scans are assumed identical, and any changes made to a scan
parameter will be applied to all scans of the series.

Unique Scans: When clicked, sets the Edit Mode to be for unique scans. Unlike the Identical Scans
button, clicking on Unique Scans does not change any run parameters but only changes the
current edit mode. Additionally, while this button is selected then all scans are assumed unique.
Thus, any changes made to a scan parameter will be applied only to the currently highlighted scan
or scans. Multiple scan selection can be achieved by clicking on any number of scans in the list,
while the Ctrl key is also pressed.

Even/Odd: Allows you to easily configure the instrument for alternating up and down scans. Clicking on
the Even button will select (highlight) all even numbered scans, and will cause for all ensuing
changes to scan parameters to be assigned to all even numbered scans. Clicking on the Odd
button will select (highlight) all odd numbered scans, and will cause for all ensuing changes to
scan parameters to be assigned to all odd numbered scans.

Found below is the definition for all of the scan parameters:

Starting Temperature: The starting temperature of a scan. If the Starting Temperature of a scan is less
than the Final Temperature of that same scan then the scan will be an upscan. If not, then the
scan will be a downscan.

Final Temperature: The ending temperature of a scan. If the Final Temperature of a scan is greater than
the Starting Temperature of that same scan then the scan will be an upscan. If not, then the scan
will be a downscan.

ScanRate: The rate at which the VP-DSC will be scanned in temperature. This parameter box only
accepts positive values as upscans. Upscans and downscans are distinguished from one another
by their Starting Temperature and their Final Temperature and not by the sign of the scanrate. A
maximum of 90 Deg./Hr. for upscans and 60 Deg./Hr. for downscans is recommended for optimal
results.

PreScan Thermostat: The amount of time to thermostat at Starting Temperature, prior to beginning the
scan. This allows for thorough equilibration of the thermal core of the VP-DSC before beginning
the scan. This parameter can affect the repeatability and the shape of the baseline. The default
value of 15 minutes is recommended.

MAU120030 Rev B -28-

_______ ___ Section 3.3 – DSC Controls Windows

PostScan Thermostat: The amount of time to thermostat at Final Temperature prior to beginning the next
scan. The PostScan Thermostat period is typically used only for cleaning purposes, in order to
incubate the DSC cells at a high temperature for a specified period of time. In general, there are
no performance gains to be had by specifying a post-run thermostat period during normal DSC
operation.

Filtering Period: The time period over which data samples are averaged and a data point is generated and
stored. For protein transitions, a filter period in the range of 10-20 seconds is usually appropriate.
For sharper transitions such as lipids, a shorter filter period of 1-5 seconds is usually appropriate.

Data File Name: The file name under which all experimental data will be saved. All VP-DSC data files
will have a .dsc extension.

FB Mode/Gain: Determines the method and magnitude of cell-cell compensation used for thermal
equilibration of the reference and sample cells. Each of the 4 available FB Modes is pre-
calibrated.
When the None (or passive) FB Mode is chosen, then there will be no active cell-cell
compensation in response to temperature differences between the reference and sample cells.
Equilibration of the cells will be achieved ‘passively’ through thermal conduction and
convection. While this method provides for the highest sensitivity (short-term noise), it also
provides for the slowest response time of the DP signal. This feedback mode is appropriate for
almost all protein studies (broad transitions).
When the Low, Mid or High FB Mode is chosen, then there will be active compensation to the
cell(s) in response to temperature differences between them. The colder cell will always receive
the compensation, and the amount of compensatory heat for a given temperature difference will
vary depending on the FB Mode chosen. Low gain will provide for less compensation than will
mid gain, which will provide less compensation than will high gain.
High gain feedback mode will provide for the greatest amount of cell-cell compensation for any
given temperature difference between the cells. The result, when working in High Gain FB Mode
will be a faster response time, but with higher short term noise in the DP data. This mode, and its
fast response is usually necessary when studying very sharp thermal transitions such as Lipids.
The low and mid gain feedback modes will provide intermediate levels of sensitivity and
response time characteristics, as compared with the No Gain and High Gain feedback modes.

Data File Comments: In addition to the run parameters and data file names, Data File Comments can be
assigned for each scan. These comments get saved as part of the data file header and can be
viewed from the data analysis program, or from any text editor such as Word or NotePad. When
entering data file comments please remember that the Scan Edit Mode will be ignored. Data File
Comments will be applied to all selected scans only, or may be applied to all scan by clicking on
the Apply Comments To All option.

Cell Refill Parameters: The Cell Refill Parameters, available from the DSC Control window are useful
for getting the best performance from your VP-DSC. Since the VP-DSC works best while it is
cycling (see Sections 4.6 and 5 of this manual), cell refilling must be done during the cooling
cycle between scans. The Cell Refill Parameters are provided to help users refill the DSC cell(s)
at approximately the same temperature each time, and while the DSC is cycling.
You first activate the audible cell filling warning by clicking on Use Audible Fill Indicator. This
indicates that you want to be warned, audibly, when the cell temperature is within the specified

-29- MAU120030 Rev B

Section 3.3—DSC Controls Windows

temperature window. Next, you can define the temperature window during which you want to
refill the cells. Enter the desired minimum and maximum temperatures during which you want to
refill. A 10 degree temperature window, well below any regions of sample transition is
suggested. During between scan cooling, and when the cells pass into this temperature window,
VPViewer will beep periodically and will indicate that it is time to refill the cells. The beep
continues until you clear the message (click on OK in message window), or until the cell
temperature passes outside of the refill temperature window.

MAU120030 Rev B -30-

_______ ___ Section 3.5 – Setup/Maintenance Window

Section 3.4

Thermostat/Calibration Window

This window allows access to the thermostat control and DP calibration pulse function. The window is
displayed below:

Thermostat Control: Allows for setting of the thermostat temperature, which will be maintained during
the VP-DSC Thermostatting state. Pre-thermostatting the VP-DSC and samples will result in
shorter equilibration times. Additionally, high temperature thermostatting during cell cleaning can
often times improve the effects of the cleaning.

Pulse Control: Allows for manually administering a DP calibration pulse. While this is not the most
thorough method of checking the y-axis calibration, it is the quickest and most convenient
method. Pulses may be applied any time the DP signal is equilibrated and the resulting deflection
used as a crude calibration assessment. Using a pulse which is relatively large ( > +/- 5
mCal/min.) will expose DP calibration errors greater than 1%. Any users who feel that the y-axis
calibration requires adjustment should contact Microcal prior to attempting any changes to the
VP-DSC calibration constants.

-31- MAU120030 Rev B

Section 3.5—Setup/Maintenance Window

Section 3.5

Setup/Maintenance Window
This window allows access to user preferences. Displayed below is the Setup/Maintenance window,
along with the default settings for the user preferences. Systems having multiple users may benefit from
using customized preferences, linked to a particular user name. Please see Section 3.6 of this manual for

more details on Customizing VPViewer.

Definitions of the individual preferences can be found immediately below:

Data File Path: Indicates the complete path (excluding file name) where all VP-DSC data files will be
saved. The specified path should be located on a hard drive and not on any floppy or CD-ROM
drives. This setting may only be changed while the VP-DSC is in the idle state, Thermostatting.
To change the current data file path, double click on the existing path text and a dialog box will
open allowing you to change the current path. The desired data directory must already exist in
order to select it from the dialog box.

Setup File Path: Indicates the complete path (excluding file name) where all VP-DSC setup files will be
saved and loaded. The specified path should be located on a hard drive and not on any floppy or
CD-ROM drives. To change the current setup file path, double click on the existing path text and
a dialog box will open allowing you to change the current path. The desired setup directory must
already exist in order to select it from the dialog box.

MAU120030 Rev B -32-

_______ ___ Section 3.5 – Setup/Maintenance Window

Init. Setup File: Specifies the initial setup file which will be loaded into the experimental control
window, the first time it is opened. Specifying a *.scn file here will result in an initial DSC Scan
Mode of Conventional DSC. Specifying a *.iso file here will result in an initial DSC Scan Mode
of Isothermal Scan Mode. Lastly, specifying a *.pps file (only for those users having the PPC
accessory) will result in an initial DSC Scan Mode of Compressability Mode.
As an alternative approach, specifying the initial setup file as LastRun1.scn will result in the last
run parameters that were executed to be loaded at startup. The initial DSC Scan Mode will then
be set to the same mode as was used for the last executed scan.

Boot Temperature: Determines the initial VP-DSC thermostat temperature upon launching the VPViewer
application. Immediately after starting VPViewer the system will enter the Thermostatting state,
go to the specified boot temperature and thermostat.

Y-Axis Scale: Allows for changing of the current y-axis (DP) units. Available y-axis units are mCal/min.,
µCal/sec. and µWatts. By default, y-axis units will be displayed in mCal/min. It must be realized
that changing y-axis units in this manner will only change the power units for ‘local’ data
displayed in real-time, within VPViewer and Origin (for real-time data display). All data files
will be saved with the default units of mCal/Min.

Export Current Data: Typically only used for diagnostics. Users may be instructed by a MicroCal
technician to Export Current Data, for use in troubleshooting. It provides service personnel with
a convenient means of capturing DSC data, which otherwise is not saved to disk.

Plot Idle Data: Typically only used for diagnostics. Users may be instructed by a MicroCal technician to
Plot Idle Data, for use in troubleshooting. It provides service personnel with a convenient means
of capturing DSC data, which otherwise is not saved to disk.

Extended Data Mode: Typically only used for diagnostics. This mode of operation will save all of the
data channels the VP instrument produces to the data file. This function is used to provide
Microcal engineers with extra data for troubleshooting.

Save/Add/Erase user: These buttons provide a convenient way of maintaining the desired startup
parameters for multiple users. The primary use is for separating data files in different directories.

-33- MAU120030 Rev B

Section 3.7—Constants Window

Section 3.6

Constants Window
Provides viewing access to the calibration constants for your particular VP-DSC instrument. Shown
below are calibration constants that are typical of the VP-DSC. This window is password protected and
should not be changed without authorization by a MicroCal Engineer.

MAU120030 Rev B -34-

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